Commit 1254c70d authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r316035: 

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r316035 | tnorthover | 2017-10-17 14:43:52 -0700 (Tue, 17 Oct 2017) | 6 lines

AArch64: account for possible frame index operand in compares.

If the address of a local is used in a comparison, AArch64 can fold the
address-calculation into the comparison via "adds". Unfortunately, a couple of
places (both hit in this one test) are not ready to deal with that yet and just
assume the first source operand is a register.
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llvm-svn: 319231
parent 041898d2

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

+6 −0
Original line number Diff line number Diff line
@@ -940,6 +940,12 @@ bool AArch64InstrInfo::areMemAccessesTriviallyDisjoint( 
bool AArch64InstrInfo::analyzeCompare(const MachineInstr &MI, unsigned &SrcReg,

                                      unsigned &SrcReg2, int &CmpMask,

                                      int &CmpValue) const {

  // The first operand can be a frame index where we'd normally expect a

  // register.

  assert(MI.getNumOperands() >= 2 && "All AArch64 cmps should have 2 operands");

  if (!MI.getOperand(1).isReg())

    return false;



  switch (MI.getOpcode()) {

  default:

    break;

llvm/lib/Target/AArch64/AArch64RedundantCopyElimination.cpp

+3 −0
Original line number Diff line number Diff line
@@ -167,6 +167,9 @@ AArch64RedundantCopyElimination::knownRegValInBlock( 
    // CMP is an alias for SUBS with a dead destination register.

    case AArch64::SUBSWri:

    case AArch64::SUBSXri: {

      // Sometimes the first operand is a FrameIndex. Bail if tht happens.

      if (!PredI.getOperand(1).isReg())

        return None;

      MCPhysReg SrcReg = PredI.getOperand(1).getReg();



      // Must not be a symbolic immediate.

llvm/test/CodeGen/AArch64/cmp-frameindex.ll

0 → 100644
+19 −0
Original line number Diff line number Diff line 
; RUN: llc -mtriple=aarch64 %s -o - | FileCheck %s



; CHECK: test_frameindex_cmp:

; CHECK: cmn sp, #{{[0-9]+}}

define void @test_frameindex_cmp() {

  %stack = alloca i8

  %stack.int = ptrtoint i8* %stack to i64

  %cmp = icmp ne i64 %stack.int, 0

  br i1 %cmp, label %bb1, label %bb2



bb1:

  call void @bar()

  ret void



bb2:

  ret void

}



declare void @bar()